17. Shiny Web Apps

What is Shiny?

Shiny is an R-based environment for building interactive web applications for
data analysis and exploration. Since most JavaScript code is autogenerated by
the environment, basic R knowledge is sufficient for developing Shiny apps.
They can be deployed on local computers or web servers including custom and cloud-based servers (e.g.
AWS, GCP, shinyapp.io service). The basic structure of a Shiny app is an
app.R script containing the following components:

User interface

ui<-fluidPage()

Server function

server<-function(input,output){}

Statement to run shiny app

shinyApp(ui=ui,server=server)

Alternatively, the ui and server functions can be organized in two script files, a ui.R and a server.R script, respectively.

Develop and test Shiny app locally

Open R and set session to parent directory (here myappdir) containing shiny script app.R, and the
run it with the runApp() function. A sample app.R script for testing can be downloaded from here.

library(shiny)runApp("myappdir")# To show code in app, add argument: display.mode="showcase"

This will open the app in a web browser.

Deploy on web server

This can be done on local or cloud systems. An easy solution is to get an account on shinyapps.io
and then deploy Shiny apps there. For details, see here.

setwd("myappdir")library(rsconnect)deployApp()

Example Shiny app

The following Shiny app is hosted on shinyapps.io and embedded into the markdown (or html) source of this page
using the following iframe syntax:

Learning Shiny

The Shiny section on the Rstudio site contains excellent tutorials.
In addition, users may want to explore the example apps included in the shiny package. This can be
done by loading the individual examples (see here) or saving
the code to a user writable directory like this: